Hi,
The folks here at TeamTalk have become my "go to" source for MC information, the people here are great! Hopefully someone can help me out.
We've got a 2001 X-30 with the 330 LTR multi-point injection engine. We took it out for the first time this season and it ran fine but the check engine light would come on after a couple of minutes above 3000 RPM.

I shorted pins A-B on the ECM diagnostic connector and the check engine light flashed code 44.
I've looked for this on a lot of forum posts here, but haven't found this code mentioned (except for a different engine I did see one mention of a 44 code).

The posts on TeamTalk that mention engine codes refer to the standard GM codes. A code 44 in the GM manuals is an O2 sensor voltage low code.
From my understanding, this motor operates in an "open loop" mode and does not have an O2 sensor... so why am I getting an O2 sensor code?

Since the LTR only has 1 knock sensor (IIRC), check the connection to the knock sensor and if the wiring looks good, replace the knock sensor. Should be $30-$40 at an auto parts store.

The knock sensor on the LTR is in the port side block drain plug. Since this was your first time out this season, I'd bet the knock sensor wasn't re-connected after de-winterizing the boat. Might just need to simply plug the wire back on there.

Hey, Fantastic!
I knew the TT crowd would come through for me!
Can you tell me what manual you found that information in and where you got the manual?
I downloaded all the "operators" manuals I could find on Indmar's web site, but they didn't list any codes...
Thanks again!

Just got back from a test drive at the lake today, and the check engine light woes are completey gone, thanks to excellent TeamTalk advice!

I ordered a new knock sensor from the dealer (who had to get it from Indmar-- expedited shipping in order to make it in time for last weekends boat-fixing session). The sensor was easy to replace and problems are all gone.

I did note that the plastic connector on the old sensor was a bit cracked/chipped, perhaps it was making bad contact causing the problem.

I ordered it through the dealer figuring it might be a marinized version of the sensor, but it came in an ordinary AC Delco parts bag-- so anyone else needing the sensor might be able to find more locally and cheaper than going through the dealer to Indmar. I've attached a photo of the sensor and the bag for part number references...
(2001 X-30 with 330 LTR engine -- knock sensor part number)

I had to guess which connector was the correct one to check codes- -turns out there was more than one connector with "A" and "B" pins on it. Here's a pic of the engine diagnostic connector on my boat (2001 X-30 with 330 LTR) for anyone who's wondering what it looks like...